drivers/hwmon/ds1621.c

   1 /*
   2  * (C) Copyright 2001
   3  * Erik Theisen,  Wave 7 Optics, etheisen@mindspring.com.
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 /*
   9  * Dallas Semiconductor's DS1621/1631 Digital Thermometer and Thermostat.
  10  */
  11
  12 #include <common.h>
  13 #include <i2c.h>
  14 #include <dtt.h>
  15
  16 /*
  17  * Device code
  18  */
  19 #define DTT_I2C_DEV_CODE        0x48    /* Dallas Semi's DS1621 */
  20 #define DTT_READ_TEMP           0xAA
  21 #define DTT_READ_COUNTER        0xA8
  22 #define DTT_READ_SLOPE          0xA9
  23 #define DTT_WRITE_START_CONV    0xEE
  24 #define DTT_WRITE_STOP_CONV     0x22
  25 #define DTT_TEMP_HIGH           0xA1
  26 #define DTT_TEMP_LOW            0xA2
  27 #define DTT_CONFIG              0xAC
  28
  29 /*
  30  * Config register bits
  31  */
  32 #define DTT_CONFIG_1SHOT        0x01
  33 #define DTT_CONFIG_POLARITY     0x02
  34 #define DTT_CONFIG_R0           0x04    /* ds1631 only */
  35 #define DTT_CONFIG_R1           0x08    /* ds1631 only */
  36 #define DTT_CONFIG_NVB          0x10
  37 #define DTT_CONFIG_TLF          0x20
  38 #define DTT_CONFIG_THF          0x40
  39 #define DTT_CONFIG_DONE         0x80
  40
  41
  42 int dtt_read(int sensor, int reg)
  43 {
  44         int dlen;
  45         uchar data[2];
  46
  47         /* Calculate sensor address and command */
  48         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
  49
  50         /* Prepare to handle 2 byte result */
  51         switch(reg) {
  52         case DTT_READ_TEMP:
  53         case DTT_TEMP_HIGH:
  54         case DTT_TEMP_LOW:
  55                 dlen = 2;
  56                 break;
  57         default:
  58                 dlen = 1;
  59         }
  60
  61         /* Now try to read the register */
  62         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  63                 return 1;
  64
  65         /* Handle 2 byte result */
  66         if (dlen == 2)
  67                 return (short)((data[0] << 8) | data[1]);
  68
  69         return (int)data[0];
  70 }
  71
  72
  73 int dtt_write(int sensor, int reg, int val)
  74 {
  75         int dlen;
  76         uchar data[2];
  77
  78         /* Calculate sensor address and register */
  79         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  80
  81         /* Handle various data sizes. */
  82         switch(reg) {
  83         case DTT_READ_TEMP:
  84         case DTT_TEMP_HIGH:
  85         case DTT_TEMP_LOW:
  86                 dlen = 2;
  87                 data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
  88                 data[1] = (char)(val & 0xff);
  89                 break;
  90         case DTT_WRITE_START_CONV:
  91         case DTT_WRITE_STOP_CONV:
  92                 dlen = 0;
  93                 data[0] = (char)0;
  94                 data[1] = (char)0;
  95                 break;
  96         default:
  97                 dlen = 1;
  98                 data[0] = (char)(val & 0xff);
  99         }
 100
 101         /* Write value to device */
 102         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 103                 return 1;
 104
 105         /* Poll NV memory busy bit in case write was to register stored in EEPROM */
 106         while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB)
 107                 ;
 108
 109         return 0;
 110 }
 111
 112
 113 int dtt_init_one(int sensor)
 114 {
 115         int val;
 116
 117         /* Setup High Temp */
 118         val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
 119         if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
 120                 return 1;
 121
 122         /* Setup Low Temp - hysteresis */
 123         val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 124         if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
 125                 return 1;
 126
 127         /*
 128          * Setup configuraton register
 129          *
 130          * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
 131          *
 132          * We run in polled mode, since there isn't any way to know if this
 133          * lousy device is ready to provide temperature readings on power up.
 134          */
 135         val = 0x9;
 136         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 137                 return 1;
 138
 139         return 0;
 140 }
 141
 142 int dtt_get_temp(int sensor)
 143 {
 144         int i;
 145
 146         /* Start a conversion, may take up to 1 second. */
 147         dtt_write(sensor, DTT_WRITE_START_CONV, 0);
 148         for (i = 0; i <= 10; i++) {
 149                 udelay(100000);
 150                 if (dtt_read(sensor, DTT_CONFIG) & DTT_CONFIG_DONE)
 151                         break;
 152         }
 153
 154         return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 155 }